87 lines
2.0 KiB
Perl
87 lines
2.0 KiB
Perl
#!/usr/bin/perl
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use strict;
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use warnings "all";
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use Fcntl;
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my $fname = undef;
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if(defined($ARGV[0])){
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if($ARGV[0] eq "--help"){
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syswrite STDOUT, "Usage: $0 <filename>\n";
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syswrite STDOUT, "or pipe data thrugh $0's STDIN to $0 STDOUT\n";
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exit 0;
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}
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$fname = $ARGV[0];
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}
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my $byte;
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my $counter = 1;
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my $block_size = 65536;
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my $first_remembered_byte = undef;
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my $second_remembered_byte = undef;
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if (defined($fname)){
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sysopen(STDIN, $fname, O_RDONLY) or die "Can not open file $fname!\n";
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sysopen(STDOUT, "$fname.rle", O_WRONLY|O_TRUNC|O_CREAT) or die "Can not open file $fname.rle!\n";
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}
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binmode(STDIN);
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binmode(STDOUT);
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exit 0 if ((sysread(STDIN, $byte, 1)) == 0);
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$first_remembered_byte = $byte;
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my $output_buf_byte_counter = 0;
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my $output_buf = '';
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my $input_buf = '';
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while ( 1 ) {
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my $read_bytes = sysread(STDIN, $input_buf, $block_size);
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last if($read_bytes == 0);
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my $i = 0;
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for ( $i = 0; $i < $read_bytes; $i++ ) {
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$byte = substr( $input_buf, $i, 1);
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last unless(defined($byte));
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$second_remembered_byte = $first_remembered_byte;
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$first_remembered_byte = $byte;
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if(($first_remembered_byte eq $second_remembered_byte) and ($counter <= 254)){
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$counter++;
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next;
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}
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if ($output_buf_byte_counter == $block_size){
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syswrite STDOUT, $output_buf || die "Cannot write output stream!\n";
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$output_buf = '';
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$output_buf_byte_counter = 0;
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}else{
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$output_buf_byte_counter++;
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}
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$output_buf .= chr($counter) . $second_remembered_byte;
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$second_remembered_byte = $first_remembered_byte;
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$counter = 1;
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}
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undef $i;
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undef $read_bytes;
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}
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close(STDIN);
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# 0-byte string
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exit 0 unless (defined($first_remembered_byte));
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# 1-byte string
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unless(defined($second_remembered_byte)){
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$output_buf = chr($counter) . $first_remembered_byte;
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}else{
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# 2+ bytes string
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$output_buf .= chr($counter) . $second_remembered_byte;
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}
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syswrite STDOUT, $output_buf || die "Cannot write output stream!\n";
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close(STDOUT);
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undef $fname;
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undef $counter;
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undef $first_remembered_byte;
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undef $second_remembered_byte;
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undef $byte;
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undef $input_buf;
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undef $output_buf;
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